Canine retina has a primate fovea-like bouquet of cone photoreceptors which is affected by inherited macular degenerations

PLoS One. 2014 Mar 5;9(3):e90390. doi: 10.1371/journal.pone.0090390. eCollection 2014.

Abstract

Retinal areas of specialization confer vertebrates with the ability to scrutinize corresponding regions of their visual field with greater resolution. A highly specialized area found in haplorhine primates (including humans) is the fovea centralis which is defined by a high density of cone photoreceptors connected individually to interneurons, and retinal ganglion cells (RGCs) that are offset to form a pit lacking retinal capillaries and inner retinal neurons at its center. In dogs, a local increase in RGC density is found in a topographically comparable retinal area defined as the area centralis. While the canine retina is devoid of a foveal pit, no detailed examination of the photoreceptors within the area centralis has been reported. Using both in vivo and ex vivo imaging, we identified a retinal region with a primate fovea-like cone photoreceptor density but without the excavation of the inner retina. Similar anatomical structure observed in rare human subjects has been named fovea-plana. In addition, dogs with mutations in two different genes, that cause macular degeneration in humans, developed earliest disease at the newly-identified canine fovea-like area. Our results challenge the dogma that within the phylogenetic tree of mammals, haplorhine primates with a fovea are the sole lineage in which the retina has a central bouquet of cones. Furthermore, a predilection for naturally-occurring retinal degenerations to alter this cone-enriched area fills the void for a clinically-relevant animal model of human macular degenerations.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Chloride Channels / genetics
  • Dog Diseases / genetics
  • Dog Diseases / pathology*
  • Dogs
  • Eye Proteins / genetics
  • Fovea Centralis / pathology*
  • Macular Degeneration / genetics
  • Macular Degeneration / pathology
  • Macular Degeneration / veterinary*
  • Mutation
  • Retina / pathology
  • Retinal Cone Photoreceptor Cells / pathology*

Substances

  • Chloride Channels
  • Eye Proteins